The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
In general, an environmentally friendly vehicle (a hybrid vehicle or an electric vehicle) may generate a driving torque by an electric motor (hereinafter referred to as “drive motor”) which gains a rotating force based on electrical energy.
A hybrid vehicle runs in an electric vehicle (EV) mode, which is a pure electric mode using only power of a drive motor. Alternatively, the hybrid vehicle runs in a hybrid electric vehicle (HEV) mode, which uses driving torques of both an engine and the drive motor for power. Further, a general electric vehicle runs by using a torque of the drive motor as a power source.
For example, a drive motor used as a power source for an environmentally friendly vehicle is generally a permanent magnet synchronous motor (PMSM).
The drive motor as a PMSM serving as a power source of the environmentally friendly vehicle includes a stator to generate a magnetic flux, a rotor spaced apart from the stator by a predetermined gap, and a permanent magnet installed at the rotor.
In this case, the stator includes a plurality of slots which are formed at an inner peripheral portion of a stator core, and a stator coil that is wound in the slots. Accordingly, if an AC current is applied to a stator coil, the stator core is electro-magnetized, and the electro-magnetized stator core, the stator core by an N pole and an S pole and the drive motor as attractive or repulsive force may generate rotation torque.
Meanwhile, a winding path of the stator coil included in the stator may be a series or parallel circuit depending on design of the drive motor. Also, direction of current flowing along the winding path of the stator coil may reverse so that the stator generates alternative magnetic field.
Direction of a coil of stator coil winding in a conventional art is set as in/out so that the stator coil winding may generate alternative magnetic field in a predetermined regulation. However, the winding of the stator coil where in/out direction is predetermined may have a phase draw out part with an excessively high resistance of the stator coil. Further, when the resistance of the phase draw out part creates a deviation, low performance of a motor may be occurred by applied power imbalance (current imbalance), resistance imbalance, torque imbalance and torque ripple.